Life Stage Applicability

Key Event Relationship Description

Evidence Supporting this KER

Biological Plausibility

In mammals androgen production by theca cells is largely under control of LH (Norris 2007; Young and McNeilly 2010).

In fish, the differential role of LH versus FSH has been more difficult to define, in part due to the inability to specifically measure LH and FSH in most fish species and the parallel fluctuations of LH and FSH expression in many species.

Regardless of the differential effects of the two gonadotropins there is little dispute that gonadotropins stimulate gonadal steroid production and that the production of androgens (e.g., androstenedione, testosterone), which are the precursors for estrogen synthesis occurs in the theca cells (Payne and Hales 2004; Young and McNeilly 2010; Miller 1988; Nagahama et al. 1993).

Known Feedforward/Feedback loops influencing this KER

Domain of Applicability

The taxonomic applicability of this key event is limited to chordates.

CYP11a, one of the critical enzymes for testosterone synthesis has only been found in amphioxus or vertebrates (Baker 2011). Consequently, taxonomic relevance of this KER is likely restricted to that domain.